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Finding the Fourth Proportional to 991.07, 1,486.38 and 638.61

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Solution

The fourth proportional to 991.07, 1,486.38 and 638.61 is: 957.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.07 : 1,486.38 = 638.61 : x
  2. Step 2: Convert to fraction form
    991.07/1,486.38 = 638.61/x
  3. Step 3: Cross multiply
    991.07x = 1,486.38 × 638.61
  4. Step 4: Simplify right side
    991.07x = 949,217.13
  5. Step 5: Solve for x
    x = 949,217.13/991.07
  6. Step 6: Final answer
    x = 957.77

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.